For the sake of convenience we may classify the methods of squaring-up stock under the following heads; squaring-up mill-planed stock for (1) outside finish; (2) inside finish; (3) squaring up rough-sawed stock or mill-planed stock where accuracy is very important. In reality there is but one method of squaring-up stock - number three -the others being modifications of the order for this.
The simplest process of squaring-up stock is that used in preparing stock for outside building finish, such as base, corner boards, cornice members, etc. For this purpose mill-planed stock is made use of, stock thicknesses being specified. Since such finish is usually painted, and, being on the outside, does not require a fine treatment, nothing is done to the broad surfaces, not even planing off the mill-marks or sandpapering. Many manual training shop problems, such as cutting-boards, bird houses, etc., may be treated in this same manner.
A larger number of manual training projects will make use of the second method of squaring-up stock - that used in preparing interior building finish. This differs from the one just described in that, being intended for inside work where the surfaces will be stained and waxed or varnished, the mill-marks must be removed from one or both broad surfaces, and these sandpapered well. Like outside finish, inside finish, too, does not require that its broad surfaces be perfectly true or out of wind, merely smooth. The reason stock slightly warped will answer for all exterior and most interior finish is due to the fact that most of the wind can be "nailed out" in assembling, Fig. 101.
Projects in furniture construction and in patternmaking, however, do not as a rule have assemblies which permit of "nailing out" warp or wind. For this reason a third method, more difficult than those mentioned, is required in which the first surface must be made true, with warp and wind removed. A uniform thickness is gaged from this trued surface.